Photochemistry Journey to Multielectron and Multiproton Chemical Transformation

Abstract

The odyssey of photochemistry is accompanied by the journey to manipulate “electrons” and “protons” in time, in space, and in energy. Over the past decades, single-electron (1e–) photochemical transformations have brought marvelous achievements. However, as each photon absorption typically generates only one exciton pair, it is exponentially challenging to accomplish multielectron and proton photochemical transformations. The multistep differences in thermodynamics and kinetics urgently require us to optimize light harvesting, expedite consecutive electron transfer, manipulate the interaction of catalysts with substrates, and coordinate proton transfer kinetics to furnish selective bond formations. Tandem catalysis enables orchestrating different photochemical events and catalytic transformations from subpicoseconds to seconds, which facilitates multielectron redox chemistries and brings consecutive, value-added reactivities. Joint efforts in molecular and material design, mechanistic understanding, and theoretical modeling will bring multielectron and proton synthetic opportunities for fuels, fertilizers, and chemicals with enhanced versatility, efficiency, selectivity, and scalability, thus taking better advantage of photons (i.e., sunlight) for our sustainable society.

Room-temperature photosynthesis of propane from CO2 with Cu single atoms on vacancy-rich TiO2

“…29 . In summary, the above results suggest a tandem catalysis mechanism 13 – 16 , 54 – 56 , where the Cu-free Ti 0.91 O 2 matrix may be preferential to participate in the reduction of CO 2 to CO, and Cu-Ti-V O unit is more beneficial to the exergonic C-C coupling to C 2+ products (Supplementary Fig. 30 ).…”

Photocatalytic hydrogen evolution and simultaneously converting high-concentration of thiols into disulfides with excellent yield under visible-light

“…Fortunately, the dual-function photocatalytic system has provided an ideal way to solve this problem, wherein photogenerated electrons and holes are simultaneously used to reduce and oxidize reactants, respectively. [14][15][16] Theoretically, the dual-function photocatalytic systems can maximize the usage of solar energy and be extremely efficient. 17,18 Nevertheless, there is still a big challenge in the dual-function photocatalytic system, that is, mostly the concentration of substrates is still at the level of a few millimoles under ambient temperature and pressure and the yield is not satisfactory, which is far from the requirement of the large-scale practical applications.…”

Visible Light Photocatalytic Hydrogen Evolution Paired with Excellent Intramolecular Coupling of Dithiols into Sulfurous Heterocyclic Compounds over CdS/P25/Ni2P

“…Visible light photocatalytic synthesis has become a more attractive approach than the conventional methods through stoichiometric oxidants for its high synthetic potential and has made great strides in recent years, which can avoid the generation of detrimental pollutants under mild conditions. − Recently, a photooxidation method was introduced, which was applicable to realize the lactonization of diols with sunlight as the sole energy . However, the selectivity and conversion of such reactions are generally at a low benchmark, which restricts the development of photocatalytic synthesis technology. , Considering the maximum usage of solar energy and improvement of whole economic efficiency, it is meaningful to find a method for synchronously using the photogenerated electrons and holes to efficiently conduct chemical reactions …”

“…31,32 Considering the maximum usage of solar energy and improvement of whole economic efficiency, it is meaningful to find a method for synchronously using the photogenerated electrons and holes to efficiently conduct chemical reactions. 33 Recent developments in hydrogen production have provided evidence that a dual-function photocatalytic system is an excellent project due to this technology, making green hydrogen evolution and nonhazardous substrate conversion under visible light. 34−36 Besides, as for the dual-function photocatalytic system, the photogenerated carriers can react with the substrates directly, avoiding the production of reactive radical intermediates; such systems exhibit a high yield for target products.…”